The working and the service life of the roller bearing is determined, in particular, by the quality of the seal. Vehicle manufacturers call for roller bearings, for belt drives of the internal combustion engine, for example, to be designed for the life of the vehicle.
Patent specification DE 41 33 777 C2 discloses a seal for a roller bearing, which is integrated into a tensioning roller of a belt drive. On both sides of the rolling elements the known seal comprises sealing plates, which are positioned on the rotating outer bearing ring and which on the inner side rub on the supporting inner bearing ring. Such a seal affords the roller bearing limited protection against splash water and the ingress of contaminants into the roller bearing, and provides a lubricant outlet from the roller bearing. This known seal is unsuitable, for example, for vehicles used in off-road operation, which are designed for running through water and which are exposed to massive ingress of dirt into the space provided for installation of the internal combustion engine.
One known measure designed to improve the sealing properties of roller bearing seals are covers which serve to partially cover the front face of the roller bearing. DE 953 597, for example, shows a seal which comprises two separate, elastic seals, the seal lips of which rub on a supporting sleeve enclosing the shaft. Two cover/sealing plates arranged separately from one another are furthermore placed in front of these seals. On the outside, a cover plate fixed to the housing is provided, through the central opening in which the shaft is led. A second rotating sealing plate is fixed in position on the shaft. The structure of this known seal for a roller bearing requires a large overall axial length and with two seal lips designed to rub furthermore generates a lot of heat, which has a detrimental effect on the service life of the roller bearing.